The present invention is directed to a gas discharge display device which has a front plate with a luminescent screen and an anode layer connected to a back plate having one or more cathodes mutually insulated from one another to form a gas filled cavity receiving a control plate which divides the cavity into a gas discharge space and a post acceleration space. The control plate has parallel extending column conductors on one surface, and parallel extending row conductors on the opposite surface to form a matrix of intersecting points and the plate has a perforation in each of the points.
A gas discharge display device with a cathode, which consists of cathode strips that lie parallel to one another and are insulated from one another so that they may be separately actuated or energized, is disclosed in U.S. Pat. No. 4,130,778, which was based on German O.S. 26 43 915. A subdivision of the cathode and individual cathode strips insulated from one another is an improvement over a plate cathode which was disclosed in U.S. Pat. No. 3,956,667, which was based on German application 24 12 869 and is employed for the image reproduction in so called flat picture screens or respectively, gas discharge displays.
These display devices function according to the principal of spatial separation of electron generation and electron acceleration. The tube or envelope, which is employed for that purpose, is divided into two chambers which are connected to one another via a control plate having perforations at the point of intersection of its conductors which are arranged in lines or rows and columns with the line or row of parallel conductors on one side extending perpendicular to the parallel columns on the other surface. The chamber or space between the cathode, which is preferably on the back plate of the envelope, and the strip shape auxillary anodes, which form either a line or row of the conductor matrix of the control plate coact to form the gas discharge space. The other chamber or space is a post acceleration space, which is formed between the plane of the column conductors on the control plate and plate anode which represents a luminescent screen electrode. A wedge-shaped gas discharge between the cathode and the auxillary anodes over the entire line length is produced by driving one of the auxillary anodes. Given a simultaneous drive of one of the strip-shaped control electrodes serving as the matrix columns, plasma electrons generated in the gas discharge are drawn through the opening at the point of intersection of the row and column into a post acceleration space and are accelerated toward the anode on the front surface or plate of the device. A point of light then occurs at the impact location on the luminescent substance layer which is placed on the front of the anode for each of the intersection points of the matrix that are in the drive condition. With an appropriate matrix drive in terms of chronological sequence and strength, characters and images can be displayed on the luminescent screen. A further discussion of the structure and operation of the discharge device is given in the above two U.S. Patents whose disclosures are hereby incorporated.
A flat gas discharge display element with a plurality of gas discharge cells which are arranged matrix-like, is known from U.S. Pat. No. 4,066,929, which is based on the same foreign application as German O.S. 26 01 925. In this device, a grid electrode is arranged in each cell between the anode and the cathode. The grid electrode contains at least one aperture whose edge profile is congruent with the projection of the cathode.
In known gas discharge display devices, high energy electrons generate a disruptive background brightness on the picture screen. This brightness is due to the fact that the high energy electrons are not electrically blocked at the control hole openings of the control plate. Light from the gas discharge space will also strike the picture screen through the control hole openings in the control plate to generate a background brightness.
The smaller the gas pressure in the gas discharge display device; the more apparent are these two disruptive effects. On the other hand, the puncture strength in the post acceleration space of the gas discharge display device becomes all the greater with the lower gas pressure.
In a gas discharge space of a flat gas discharge display device, metal ions will sputter off from the cathode and precipitate onto the rows or parallel extending conductors on the control plate. This precipitation of metal atoms will have a negative effect or influence on the insulation resistance between the lines.